Security is the Foundation
Proper security must be the foundation of your software. It should be the software engineer's first consideration during the planning stages of the project. If not, the results can be disastrous.
Spanning the Gap
Think of a bridge that has been designed without enough foundation in the center. Sure, it stretches the span, and cars can drives across it for awhile, but eventually it will collapse.
Software applications that are not built with the proper security are a lot like a poorly designed bridge. The application may work just fine for awhile, but as soon as a hacker finds his way in...
Unfortunately spanning the gap is often the only thing an inexperienced application developer takes into consideration. They may not even be aware that what they are building can be dangerous. It may not happen immediately, but sadly, eventually the software is broken into and it is your customers that are left in the dust.
The Highest Costs
The consequences of a collapsed bridge will unquestionably result in high repair costs, but worse, it could also mean injury or loss of life. The cost of a software breach due to lack of proper security can be equally as devastating. Theft of personal data can ruin a person's credit and ultimately even ruin their life.
Yes, safeguarding user information is essential. Beyond the terrible guilt of knowing your are responsible for whatever your users may lose, it is also extremely expensive to fix.
A 2017 study conducted by Ponemon Institute and sponsored by IBM details the cost and impact of data breaches by industry. The research shows that in 2017 the global average cost of a data breach was $3.62 million. The study also states that even though the overall costs of application security breaches decreased slightly, companies are having larger breaches. If you are a large enterprise you may be able to recover from such a large sum, but if you're a small business, you may be put out of business.
In the long run, the cost of building and maintaining a secure application is much lower than the exorbitant cost of a data breach.
Loss of Trust
One of the main costs of a data breach is the loss of trust the company will have from the consumer. This will result in loss of revenue, devaluation of the company and other costs that go beyond the hefty direct financial losses.